Highest temperature in NYC on August 18?

Platform comparison

Market context

The market seeks the highest temperature recorded at LaGuardia Airport on 18 August 2026, with the crowd currently pricing an extreme heat outcome at just 1% probability. The resolution hinges on Weather Underground's Daily Observations table rather than summary figures, a distinction that matters when peak temperatures spike briefly during afternoon hours.

New York's August heat record stands at 102°F, set in 1933. More recent context: the city has experienced only three days above 100°F since 2000, with the most recent occurring in July 2019. August typically peaks in the mid-to-high 80s Fahrenheit at LaGuardia, and temperatures consistently above 95°F remain uncommon. The 1% implied probability reflects this historical scarcity of extreme August heat, though it may undervalue the tail risk of an unusual heat dome or Atlantic ridge positioning that could drive anomalous conditions.

Traders monitoring this market should track seasonal climate forecasts from NOAA released in June and July 2026, which will indicate whether La Niña or El Niño conditions favour above-normal temperatures across the Northeast. Real-time catalysts include mid-August weather pattern shifts; a persistent high-pressure system stalling over the region could drive consecutive days of intense heat. The National Weather Service's extended outlooks in the week preceding 18 August will provide clearer signals on whether conditions favour extreme temperatures. Historical precedent suggests the crowd's low probability reflects genuine rarity, though any significant Atlantic blocking pattern would merit reassessment.

Methodology

Methodologically we separate two layers: the live probability (Polymarket mid-price) and the platform attributes (fee, KYC, settlement currency, payment rails). That keeps the comparison honest — a single canonical probability across the row, with the venue-by-venue trade-offs spelt out in the columns next to it.

Resolution & payout

Polymarket-based markets settle through the UMA Optimistic Oracle on Polygon. A proposer submits the outcome, a two-hour challenge window opens, and unchallenged proposals finalise the resolution. Payouts settle automatically in USDC the moment the result is final — no bookmaker, no delay.

Kalshi-based markets settle in USD via the CFTC-regulated clearinghouse. Betfair Exchange settles in GBP/EUR net of commission. Manifold is play-money and does not pay out real funds.

UK Frequently Asked Questions

Is this market available outside the US?

Polymarket itself is geo-blocked in the US/UK/EU. Always check the legal status of prediction markets in your jurisdiction before trading.

How does resolution work?

Through the UMA Optimistic Oracle on Polygon: a proposer submits the outcome, a two-hour challenge window opens, and USDC payouts settle automatically once the result is final.

Is Polymarket legal in the UK?

Polymarket is accessible to UK traders but is not UKGC-licensed. It operates under US CFTC jurisdiction. UK residents face no domestic legal prohibition on using it, but UKGC consumer protections do not apply. For UKGC-regulated alternatives, Betfair Exchange and Smarkets offer similar prediction-style markets.

Do I pay tax on prediction market profits in the UK?

UKGC-licensed platform profits (Betfair, Smarkets) are typically tax-free gambling winnings for UK individuals. Polymarket profits involve USDC crypto transactions, which HMRC treats as Capital Gains Tax events. Keep full transaction records and report via Self Assessment if gains exceed £3,000 per tax year.

How do I deposit on Polymarket from the UK?

UK traders typically fund Polymarket via Coinbase UK, Kraken or Revolut — buying USDC with GBP and transferring to a Polygon-compatible wallet (MetaMask, Coinbase Wallet). Polymarket's onboarding walks you through the bridging process. Typical GBP-to-USDC conversion costs 0.5–1%.